Self-loading pistols can be divided into a number of types such as pure blowback, delayed blowback, gas-operated, short-recoil-operated and long-recoil-operated.
With pure blowback pistols, the slidable superstructure consists only of a breech block slide. The slide is not locked to the barrel and the barrel is fixed to the frame. Immediately after firing, the recoil force starts to drive the slide rearwards thus commencing the extraction of the spent cartridge case. Thus, part of the extraction occurs during the high pressure period of the firing cycle. If the slide is too light, the case is extracted too soon and case rupture will result, leading to a failure of the loading cycle and possible injury to the user. As a result, the pure blowback type can only be used with low-powered cartridges since there is a practical limit to the mass of the slide. This type, however, is cheap to make and is quite common.
There are also a number of pure blowback pistols which use a gas retarding arrangement attached to the slide. The arrangement reduces the effect of residual gas pressure on the motion of the breech block slide and buffers the stop of the breech block slide.
One such gas retarding arrangement consists of a piston attached to the slide and a cylinder attached to the frame. The cylinder is connected by a passage to the barrel bore. After firing, a small amount of propellant gas is bled into the cylinder. As the slide recoils, the piston attached to the slide compresses the bled propellant gas, thus producing a retarding force.
With delayed blowback pistols, the slidable superstructure comprises a breech block slide but, as well, it has a delaying mechanism. The delaying mechanism is usually based on leverage in order to magnify the effective recoiling mass of the superstructure for a short period, thus reducing the extent of extraction of the spent cartridge case during the high pressure period of the firing cycle.
With many gas-operated pistols, the slidable superstructure comprises a breech block slide, and the pistol has a gas chamber and piston located beneath the barrel. The slide is locked to the barrel and the barrel is fixed to the frame. The gas chamber is connected by a passage to the barrel bore. After firing, the projectile travels along the barrel and passes the entrance to the passage and gas is bled into the chamber. The gas pressure drives the piston to actuate an unlocking mechanism after the high pressure period has passed. After unlocking, the breech block slide starts its rearward motion and begins extraction of the spent cartridge case using the energy provided by the piston and the residual gas pressure in the barrel. After extraction, the spent cartridge case is ejected. The slide continues until full travel is reached. The cartridge case does not move while the bullet is in the barrel. Since the case is not able to move relative to the barrel until the slide is disengaged from the barrel and the operation is not dependent on the mass of the slidable superstructure, this type is used for very powerful cartridges.
With short-recoil-operated pistols, the slidable superstructure consists of a barrel and a breech block slide. Prior to the firing of the cartridge, the barrel is engaged to the breech block slide by a locking means. After firing, the recoil force drives both the slide and barrel rearwards, but since they are in engagement, the extraction of the case has not started. After the high pressure period has passed, an actuator begins to disengage the barrel from the slide. The barrel travels a short distance before coming to rest forward of the magazine, hence short-recoil, and is completely disengaged from the slide. The breech block slide continues and begins extraction of the spent cartridge case using its kinetic energy and the residual gas pressure in the barrel. After extraction, the spent cartridge case is ejected. The slide continues until full travel is reached. The cartridge case, therefore, does not move while the bullet is in the barrel. Since the case is not able to move relative to the barrel until the barrel is disengaged from the slide, this type is used for relatively powerful cartridges. However, revolvers are generally needed for the most powerful pistol cartridges; since again, there is a practical limit to the mass of the barrel and slide on short-recoil-operated pistols.
A limitation in self-loading pistols of current design is the high level of felt recoil when using very powerful cartridges.
Cartridges of the same type with the same bullet mass, propellant and propellant loading must produce the same recoil as the laws of physics demand. This recoil force acts along the axis of the barrel. However, the axis of the barrel of a self-loading pistol is located above the pivot point in the firer's wrist and usually above the pivot point in the firer's shoulder. On firing a self-loading pistol, a moment is produced about these points. These moments produce a rotation of the firer's hand and an upward movement of the firer's arm. In addition, the slidable superstructure of a self-loading pistol moves backwards on the frame after firing and causes a shift in the centre of mass of the pistol. The final effect which occurs is the force from stopping the slidable superstructure at the end of its rearward travel. The felt recoil is the combination of the effects described above.
High felt recoil affects the first round hit probability because the firer may flinch on firing in anticipation of the recoil. High felt recoil also reduces second round hit probability as it takes the firer longer to readjust his aim for the second shot.
The distance of the barrel of a self-loading pistol from the pivot point in the firer's wrist is a result of a number of factors.
Firstly, in most self-loading pistols the magazine containing the rounds of ammunition is located in the hand grip. Since the magazine must present a round at a certain angle for stripping, the angle of the grip to the frame is determined by the angle of the magazine to the barrel bore axis. The dimensions of the grip are also determined by the magazine. The angle of the grip determines how far the wrist is able to rotate the hand of the firer forward and downward. The further the hand of the firer is rotated forward and downward, the shorter the distance between the barrel axis and the pivot in the firer's wrist.
Secondly, the size of the locking arrangements will determine how far the barrel must be positioned above the top of the magazine. The more bulky the locking arrangements, the higher the barrel must be above the top of the magazine and therefore the pivot point in the firer's wrist.
The advantage of having a sharper handgrip angle is evident in target pistols. Target pistols tend to have an handgrip angle of about 60 degrees as compared to a commercial self-loading pistol with an angle of about 75 degrees.
In contrast to the prior art self-loading pistols, it is the object of the present invention to provide a gas-operated pistol which reduces felt recoil by having a barrel mounted forward of the magazine with a barrel axis below the lips of the magazine located in the grip.